Worse than Mycroft and Sherlock
by Cumberbatch Critter
Summary: Compared to 'the other one', Mycroft and Sherlock get on like a dream. Sibling fic.


**Worse than Mycroft and Sherlock**

Sherlock was having a sulk.

Or maybe that wasn't the best word. He wasn't really pouting. He was angry, and that was the reason that his arms were crossed across his chest and he was glaring towards the window.

"Come on, Will. Don't be that way. I haven't seen you in twenty-five years, couldn't you try a _little_ bit harder to be social?"

Sherlock's head whipped around at that and, if anything, the intent look on his face only deepened. "You haven't seen me in twenty-five years because you sold out Mycroft to the Americans!"

"I did not sell him out. It's hardly my fault that he leaked sensitive information, it was his own fault for being so rambunctious."

"He was- He was _twenty_!" Sherlock spluttered. "And you were only twenty-three, like you were so much better. And I was _thirteen_ , I went from having people surrounding me to not having a brother _or_ a sister!"

"And it taught us all a valuable lesson in the end, didn't it?"

Sherlock was having a sulk because his _sister_ had shown up at Baker Street.

John hadn't even _known_ that Sherlock had other siblings, let alone that he had a _sister_. He'd been gobsmacked at first, stunned, even. Because the busty, long-legged brunette with wavy hair down to her bum that had waltzed into the flat had only pushed past him and gone upstairs without bothering with his questions of _who the hell are you_ , straight to Sherlock, who had, after freezing in his tracks, clammed up and gotten the look on his face that he was about to go nuclear.

And then it had been _"John, this is my sister. Disowned and dishonoured"_ and John was still stunned, stunned, and in the middle of a family reunion that he could only gape at. The Holmes never did anything half-arsed, especially family drama, it seemed.

"Ooh, remind me what that was?" Sherlock retorted, eyes narrowed. "That I should never trust anybody, however close to me they may be?"

"Don't be melodramatic, Will, it never suited you then and it still doesn't now."

"Runs in the family, s'pose," Sherlock snapped. He turned back to the window and then bounded to his feet, crossing the room and striding into the kitchen. "And stop lurking, John, at least you could go sit down and _try_ to stop being so obvious."

John lowered his mug. "Sorry?" He made his tone purposefully flat, raising his eyebrows as Sherlock glanced over to meet his gaze.

Sherlock did a double take and then made a noise that seemed caught between a huff and a sigh. His gaze softened slightly, although the tension didn't leave his shoulders as he reached for the coffee pot. "Sheryn and I aren't exactly on the best of terms," he said softly, although not without malice.

"Yeah, I, uh, figured that." John glanced towards Sherlock's sister - Sheryn, apparently, Sherlock hadn't given him a name before this - and then back at Sherlock. "She sold Mycroft out?"

"Essentially she started working as a spy. Given what Mycroft was doing, well, it didn't go over well. My brother made one small mistake and Sheryn attacked like a tiger on the prowl. She's been under lock and key for twenty years, the last I knew."

"You make me sound so ruthless, Sherlock, it's just a job," Sheryn called.

Sherlock's grip tightened around the mug. His knuckles were white. John knew that he didn't know the whole story, but he knew tells when he saw them and Sherlock rarely ever got angry to begin with.

"Hey," he said quietly. "Keep it together. I don't want to end up in jail with you again, okay? Don't let her get to you."

"So, is this your new boyfriend, then?" Sheryn asked, sidling into the kitchen. "John Watson, isn't it?"

John sighed, and forced a smile. "Just a colleague."

"Friend," Sherlock said.

"Friend," John repeated.

"You have _friends_ now? Well done, Willy!"

"Don't call me that!"

"Okay," John interrupted. "Let's all just go sit down and have some tea and biscuits, why don't we?"

"Needn't bother," Sherlock replied in a clipped tone. "Mycroft's on his way and Sheryn wouldn't dare be here when he arrives."

Sheryn looked at Sherlock. "Oh, no, you called big brother. Well, little brother to me all the same, but..."

"Of course I did." Sherlock took his coffee and turned back to the sitting room. "I don't know why you decided to seek me out all of a sudden, but the family status remains as it were. You shouldn't have wasted your time. Neither my brother or I have the slightest inclination towards... socialisation, and Mummy never was the same after the stunt you pulled." He sank into his chair and took a drink of his coffee.

Something Sherlock had said to Mycroft _ages_ ago suddenly clicked into place in John's mind; _"It wasn't_ me _who upset her, Mycroft!"_ Back then, John hadn't even _dreamed_ that there might have been a third Holmes sibling. He had just assumed... family rivalry between the two brothers. But if Sheryn had 'become a spy', as Sherlock had said...

 _Wow_. And that didn't even _begin_ to cover it.

John sidestepped Sheryn and followed Sherlock into the sitting room, instinctually sticking close to him. He didn't know why, asides from the small part of his mind whispering _just in case_ , but after living with Sherlock this long, he knew better than to not listen to that voice.

* * *

Sheryn left as quickly as she had come, slipping out the door mere minutes before Mycroft showed up. The exchange that had followed between the brothers was strained at best and filled with periods of awkward silence, but eventually, it was only Sherlock and John left in the sitting room.

Sherlock deflated like a popped balloon, muttering a curse that John supposed he wasn't meant to hear.

"Well."

Sherlock glanced over at him. "No, I never told you about her, no, I don't consider her part of my family, and no, I don't want to talk about it."

John had been expecting that. He held up his hands in a mock surrender sort of pose. "You don't have to. I've got family problems, too. Not of the same calibre, I guess, but..."

Sherlock looked at him stonily before cracking a smile. "Definitely not of the same calibre. Besides, you love your sister. It's a tiny bit different," he said, looking back at his refilled cup of coffee.

John ducked his head in a nod. "Yeah. Uh, sorry, though. About... whatever happened."

Sherlock looked back at him, lightning fast with inquisitive eyes. "It wasn't your fault, you weren't there."

John shrugged. "Family drama is hell."

Sherlock laughed wryly, sinking down in his chair. "Can't live with them."

"Can't live without them," John mused.

Sherlock glanced back at him again, raising one singular eyebrow. The implication there was clear: _really, John?_

"... Generally," John amended for the sake of the circumstances, and Sherlock smiled that sardonic little smile and muttered something about nicotine patches and a hot shower before getting to his feet again.

* * *

 **This was born of a conversation with ScribeofRed; what if the _other one_ is a sister instead of a brother. And since I'm in the headcanon that third sibling did something a bit not good, I still stuck with that train of thought. But can you imagine a smarter than Sherlock and Mycroft older sister in this family? Brains, beauty, and boobs. ... Or basically Sherlock in drag, but let's not go there, mmkay? xD**

 **I do not own _Sherlock_. Thanks for reading!**


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